Difference between the vortex and the wind force
This was for the use case when the cloth is pinned. Animating a flag (with a loose end) a wind force works well. 

By using a wind force the sail in the scene stopped fluttering after a few frames like blown up. Which is probably more realistic if you have steady wind from one direction.

Since I wanted it wobble I tested a vortex which  behaves more dynamically, more like a fan where the airflow changes it's strength and also allows the canvas to retract.